All salicylic acid derivatives except combinations with corticosteroids (M01B) or opioids (N02AJ) are classified in N02BA - Salicylic acid and derivatives, as it is difficult to differentiate between the use of salicylates in rheumatic conditions and other therapeutic uses of salicylates.

All plain ibuprofen preparations are classified in M01A, even if they are only intended for use as pain relief.

There are a number of combined preparations, which contain analgesics and psycholeptics. These are classified in N02, as pain relief must be regarded as the main indication. Analgesics used for specific indications are classified in the respective ATC groups. E.g.:

Combinations with opioids should be classified in N02AJ - Opioids in combination with non-opioid analgesics. Combinations with codeine, non-opioid analgesics and psycholeptics are classified in N02AA79.

Combinations with opioids and antispasmodics are classified in N02AG - Opioids in combination with antispasmodics.

Combinations with muscle relaxants are classified in M03B.

Combined preparations which contain more than one analgesic, should be classified by using the following ranking:

This means that a product containing paracetamol and phenazone should be classified in N02BE51 - paracetamol, combinations excl. psycholeptics and not in N02BB51 - phenazone, combinations excl. psycholeptics.

Dextropropoxyphene plain, and in combination with other analgesics, is classified in N02AC.

Cold preparations with therapeutic levels of analgesics are classified in this group at separate 5th levels by using the 50-series.

Preparations are subdivided on 4th levels according to chemical structure.

Combinations with ascorbic acid (i.e. 50 mg or more per unit dose) are classified at separate 5th levels using the corresponding 50-series. Products containing less than 50 mg per unit dose are classified at the plain level of the analgesic component.

The DDDs are based on approved dose recommendations.

When establishing DDDs for combination products in the 50-series, all analgesic components are taken into consideration.The DDD expressed in UD, should normally not exceed the approved dose recommendations for any of the components. See list of DDDs for combinations products, www.whocc.no.